﻿    <p>
      The <em>IfcFacetedBrep</em> is a manifold solid brep with the
      restriction that all faces are planar and bounded polygons.
    </p>
    <p>
      &nbsp;
    </p>
    <table summary="faceted brep" border="0">
      <tr>
        <td valign="top">
          <img src="../../../figures/ifcfacetedbrep_01.png" alt=
          "faceted brep instantiation" width="500" height="400">
        </td>
        <td valign="top">
          <blockquote class="note">
            NOTE&nbsp; Use of <em>IfcFacetedBrep</em> is restricted
            for boundary representation models with planar surfaces
            only. Those surfaces are implicitly represented by the
            bounding polygons. The diagram shows the topological
            and geometric representation items that are used for
            faceted breps.<br>
            <br>
            Each <em>IfcCartesianPoint</em>, used within the
            <em>IfcFacetedBrep</em> shall be referenced three times
            by an <em>IfcPolyLoop</em> bounding a different
            <em>IfcFace</em>.
          </blockquote>
        </td>
      </tr>
      <tr style="vertical-align:bottom">
        <td>
          <p class="figure">Figure 2 &mdash; Diagram showing the use of
            <em>IfcFacetedBrep</em>
          </p>
        </td>
        <td>
          &nbsp;
        </td>
      </tr>
    </table>
    <blockquote class="extDef">
      NOTE&nbsp; Definition according to ISO/CD 10303-42:1992<br>
      A faceted B-rep is a simple form of boundary representation
      model in which all faces are planar and all edges are
      straight lines. Unlike the B-rep model, edges and vertices
      are not represented explicitly in the model but are
      implicitly available through the poly loop entity. A faceted
      B-rep has to meet the same topological constraints as the
      manifold solid B-rep.
    </blockquote>
    <blockquote class="extDef">
      The faceted B-rep has been introduced in order to support the
      larger number of systems that allow boundary type solid
      representations with planar surfaces only.
    </blockquote>
    <blockquote class="note">
      NOTE&nbsp; Entity adapted from
      <strong>manifold_solid_brep</strong> defined in ISO 10303-42.
    </blockquote>
    <blockquote class="history">
      HISTORY&nbsp; New entity in IFC1.0
    </blockquote>
    <p>
      &nbsp;
    </p>
    <p class="spec-head">Informal Propositions:</p>
    <ol>
      <li>All the bounding loops of all the faces of all the shells
      in the <em>IfcFacetedBrep</em> shall be of type
      <em>IfcPolyLoop</em>.
      </li>
      <li>All vertices shall be referenced by all polyloops,
      sharing the vertex. I.e., each Cartesian point shall be
      references by at least three polyloops.
      </li>
    </ol>